CN106230762B - Doppler frequency offset estimation method and system - Google Patents
Doppler frequency offset estimation method and system Download PDFInfo
- Publication number
- CN106230762B CN106230762B CN201610602159.XA CN201610602159A CN106230762B CN 106230762 B CN106230762 B CN 106230762B CN 201610602159 A CN201610602159 A CN 201610602159A CN 106230762 B CN106230762 B CN 106230762B
- Authority
- CN
- China
- Prior art keywords
- baseband signal
- group
- signal
- indicate
- spectrum sequence
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000001228 spectrum Methods 0.000 claims abstract description 171
- 230000005540 biological transmission Effects 0.000 claims abstract description 52
- 238000012545 processing Methods 0.000 claims abstract description 33
- 230000003595 spectral effect Effects 0.000 claims description 27
- 238000004891 communication Methods 0.000 claims description 15
- 238000011835 investigation Methods 0.000 claims description 14
- 230000009466 transformation Effects 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 8
- 239000000654 additive Substances 0.000 claims description 5
- 230000000996 additive effect Effects 0.000 claims description 5
- 238000007493 shaping process Methods 0.000 claims description 4
- 230000008859 change Effects 0.000 claims description 3
- 238000013507 mapping Methods 0.000 claims description 2
- 238000011156 evaluation Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 6
- 230000008569 process Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 238000009499 grossing Methods 0.000 description 2
- 230000010363 phase shift Effects 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2626—Arrangements specific to the transmitter only
- H04L27/2627—Modulators
- H04L27/2628—Inverse Fourier transform modulators, e.g. inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2649—Demodulators
- H04L27/265—Fourier transform demodulators, e.g. fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L27/00—Modulated-carrier systems
- H04L27/26—Systems using multi-frequency codes
- H04L27/2601—Multicarrier modulation systems
- H04L27/2647—Arrangements specific to the receiver only
- H04L27/2655—Synchronisation arrangements
- H04L27/2657—Carrier synchronisation
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Discrete Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
The present invention relates to a kind of Doppler frequency offset estimation method and systems, first raw baseband signal is grouped, Fast Fourier Transform (FFT) and the disposal of gentle filter are carried out respectively to each group baseband signal group again, obtain each first signal spectrum sequence, processing is overlapped to the first signal spectrum sequence of preset group number, obtain second signal spectrum sequence, obtain the target point of amplitude maximum in second signal spectrum sequence, the free transmission range of second signal spectrum sequence is determined according to target point, and determine the amplitude central point in free transmission range, and then obtain the estimated value of the carrier frequency of raw baseband signal, the true value of the carrier frequency of estimated value and raw baseband signal further according to the carrier frequency of raw baseband signal obtains Doppler shift estimated value.The present invention mainly estimates signal carrier frequency spectrum, unrelated with Modulation Types and character rate, because of the limitation without modulated sample preparation formula, has a wide range of application, but also do not limited by character rate, expands frequency offset estimation range.
Description
Technical field
The present invention relates to digital communication technology fields, more particularly to a kind of Doppler frequency offset estimation method and system.
Background technique
In current digital communication system, since the stability and accuracy of transmitting-receiving end system crystal oscillator can not complete phases
Together, in addition the factors such as Doppler frequency shift that transceiver terminal relative motion generates, can all cause receiving end signal and send end signal
Carrier frequency can not it is identical, that is, there is certain deviation.Thus for communication system receiving end, offset estimation with
Compensating module is very important component part.
In digital communication system common at present, according to whether there is given data auxiliary to do offset estimation for offset estimation
Algorithm is divided into data auxiliary (Data-Aided, DA) and unbound nucleus (Non-Data-Aided, NDA) two major classes.In non-number
It is utilized according to given data section in the frequency excursion algorithm of auxiliary, is often not inserted into data flow for receiving end, even
The relevant parameters such as the modulation type of channel receiving signal are not all known in receiving end, at this time just bring to offset estimation sizable tired
It is difficult.
For the communication system of low character rate, it is frequently encountered the case where frequency deviation is more than character rate, as terminal is quick
Mobile low character rate satellite communication system, the Doppler frequency shift and Doppler frequency shift acceleration of system can be in the short time sharply
Increase, leading to system frequency deviation within a very short time is more than the character rate of system, and the performance of communication system is caused sharply to deteriorate.
Summary of the invention
Based on this, it is necessary to for can not determine receive signal modulation type when can not accurately carry out offset estimation with
And offset estimation receives the problem of system symbol rate limitation, provides a kind of Doppler frequency offset estimation method and system.
A kind of Doppler frequency offset estimation method, comprising the following steps:
The raw baseband signal in digital communication system channel is obtained, is counted according to preset Fast Fourier Transform (FFT) to original
Primordium band signal is grouped, and obtains each baseband signal group, wherein the symbol numbers of the baseband signal of every group of baseband signal group are
Preset Fast Fourier Transform (FFT) points；
Fast Fourier Transform (FFT) is carried out to the baseband signal in each group baseband signal group respectively, obtains each group baseband signal group
Corresponding each group discrete spectrum sequence；
The disposal of gentle filter is carried out to each group discrete spectrum sequence respectively, obtains the corresponding each group of each group discrete spectrum sequence
First signal spectrum sequence；
The first signal spectrum sequence that preset group number is chosen in each group the first signal spectrum sequence, to the of preset group number
One signal spectrum sequence carries out data investigation processing, obtains second signal spectrum sequence；
The target point for obtaining amplitude maximum in second signal spectrum sequence, determines second signal spectrum sequence according to target point
Free transmission range, and obtain the amplitude central point in free transmission range；
Obtain raw baseband signal symbol period, according to amplitude central point, preset Fast Fourier Transform (FFT) points and
Symbol period obtains the estimated value of the carrier frequency of raw baseband signal；
The true value for obtaining the carrier frequency of raw baseband signal, according to the estimated value of the carrier frequency of raw baseband signal
Doppler shift estimated value is obtained with the true value of the carrier frequency of raw baseband signal.
A kind of Doppler shift estimating system, including with lower unit:
Grouped element, for obtaining the raw baseband signal in digital communication system channel, according in preset quick Fu
Leaf transformation points are grouped raw baseband signal, obtain each baseband signal group, wherein the base band letter of every group of baseband signal group
Number symbol numbers be preset Fast Fourier Transform (FFT) points；
Spectrum processing unit, for carrying out Fast Fourier Transform (FFT) respectively to the baseband signal in each group baseband signal group,
Obtain the corresponding each group discrete spectrum sequence of each group baseband signal group；
The disposal of gentle filter unit obtains each group for carrying out the disposal of gentle filter respectively to each group discrete spectrum sequence
Corresponding the first signal spectrum of each group sequence of discrete spectrum sequence；
Superposition processing unit, for choosing the first signal spectrum sequence of preset group number in each group the first signal spectrum sequence
Column carry out data investigation processing to the first signal spectrum sequence of preset group number, obtain second signal spectrum sequence；
Passband processing unit, it is true according to target point for obtaining the target point of amplitude maximum in second signal spectrum sequence
Determine the free transmission range of second signal spectrum sequence, and obtains the amplitude central point in free transmission range；
First estimation unit, for obtaining the symbol period of raw baseband signal, according to amplitude central point, it is preset quickly
Fourier transformation points and symbol period obtain the estimated value of the carrier frequency of raw baseband signal；
Second estimation unit, the true value of the carrier frequency for obtaining raw baseband signal, according to raw baseband signal
Carrier frequency estimated value and raw baseband signal carrier frequency true value obtain Doppler shift estimated value.
It is first to divide raw baseband signal according to the Doppler frequency offset estimation method and system of aforementioned present invention
Group, then Fast Fourier Transform (FFT) and the disposal of gentle filter are carried out respectively to each group baseband signal group, obtain each first signal spectrum
Sequence is overlapped processing to the first signal spectrum sequence of preset group number, obtains second signal spectrum sequence, obtains the second letter
The target point of amplitude maximum in number spectrum sequence determines the free transmission range of second signal spectrum sequence according to target point, and determines
Amplitude central point in free transmission range, and then the estimated value of the carrier frequency of raw baseband signal is obtained, further according to original base band
The true value of the carrier frequency of the estimated value and raw baseband signal of the carrier frequency of signal obtains Doppler shift estimated value.This
The Doppler frequency offset estimation method and system of invention mainly estimate signal carrier frequency spectrum, and signal modulation pattern and is
Character rate of uniting is unrelated, because of the limitation without accredited Modulation Types, has a wide range of application, but also not by system symbol rate
Limitation, expands frequency offset estimation range.
Detailed description of the invention
Fig. 1 is the flow diagram of the Doppler frequency offset estimation method of one of embodiment；
Fig. 2 is the original signal spectrum schematic diagram of the baseband signal of one of embodiment；
Fig. 3 is the first signal spectrum schematic diagram after smothing filtering of one of embodiment；
Fig. 4 is the structural schematic diagram of the Doppler shift estimating system of one of embodiment.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention more comprehensible, with reference to the accompanying drawings and embodiments, to this
Invention is described in further detail.It should be appreciated that the specific embodiments described herein are only used to explain the present invention,
And the scope of protection of the present invention is not limited.
It is shown in Figure 1, it is the flow diagram of Doppler frequency offset estimation method in one embodiment of the invention.The implementation
Doppler frequency offset estimation method in example, comprising the following steps:
Step S101: obtaining the raw baseband signal in digital communication system channel, is become according to preset fast Fourier
It changes points to be grouped raw baseband signal, obtains each baseband signal group, wherein the baseband signal of every group of baseband signal group
Symbol numbers are preset Fast Fourier Transform (FFT) points；
This step is mainly grouped raw baseband signal, is grouped and does not generate to the property of raw baseband signal
It influences, but also is convenient for subsequent treatment process；
Step S102: Fast Fourier Transform (FFT) is carried out to the baseband signal in each group baseband signal group respectively, obtains each group
The corresponding each group discrete spectrum sequence of baseband signal group；
In this step, it is that Fast Fourier Transform (FFT) is carried out respectively to the baseband signal in every group of baseband signal group, obtains
The discrete spectrum sequence of corresponding every group of baseband signal group, this process complete baseband signal from time-domain signal to frequency-region signal
Conversion；
Step S103: the disposal of gentle filter is carried out to each group discrete spectrum sequence respectively, obtains each group discrete spectrum sequence
Corresponding the first signal spectrum of each group sequence；
Step S104: the first signal spectrum sequence of preset group number is chosen in each group the first signal spectrum sequence, to pre-
If the first signal spectrum sequence for organizing number carries out data investigation processing, second signal spectrum sequence is obtained；
In this step, the first signal spectrum sequence of preset group number is integrated into a second signal by data investigation processing
Spectrum sequence；
Step S105: the target point of amplitude maximum in second signal spectrum sequence is obtained, the second letter is determined according to target point
The free transmission range of number spectrum sequence, and obtain the amplitude central point in free transmission range；
In this step, target point and amplitude central point include spectral magnitude and spectrum position information, spectral magnitude pair
The abscissa of frequency spectrum should be corresponded in the ordinate of frequency spectrum, spectrum position；
Step S106: obtaining the symbol period of raw baseband signal, is become according to amplitude central point, preset fast Fourier
Change the estimated value of the carrier frequency of points and symbol period acquisition raw baseband signal；
Step S107: obtaining the true value of the carrier frequency of raw baseband signal, according to the carrier frequency of raw baseband signal
The true value of the carrier frequency of the estimated value and raw baseband signal of rate obtains Doppler shift estimated value.
In the present embodiment, first raw baseband signal is grouped, then each group baseband signal group is carried out respectively quickly
Fourier transformation and the disposal of gentle filter obtain each first signal spectrum sequence, to the first signal spectrum sequence of preset group number
It is overlapped processing, obtains second signal spectrum sequence, obtains the target point of amplitude maximum in second signal spectrum sequence, according to
Target point determines the free transmission range of second signal spectrum sequence, and determines the amplitude central point in free transmission range, and then obtains former
The estimated value of the carrier frequency of primordium band signal, estimated value and original base band letter further according to the carrier frequency of raw baseband signal
Number carrier frequency true value obtain Doppler shift estimated value.Doppler frequency offset estimation method and system of the invention is main
It is to estimate signal carrier frequency spectrum, it is unrelated with signal modulation pattern and system symbol rate, because without accredited number modulation sample
The limitation of formula, has a wide range of application, but also is not limited by system symbol rate, and frequency offset estimation range is expanded.
Preferably, when being grouped to raw baseband signal, when the symbol numbers of raw baseband signal are not in quick Fu
When the integral multiple of leaf transformation points, several symbols are deleted in the tail portion of raw baseband signal, make the raw baseband signal after deleting
Symbol numbers be Fast Fourier Transform (FFT) points integral multiple, since each baseband signal group can embody raw baseband signal
Frequency characteristic, therefore, Doppler shift estimation will not be had an impact by deleting the tail portion symbol of raw baseband signal.
Fast Fourier Transform (FFT) is carried out respectively to the baseband signal in each group baseband signal group in one of the embodiments,
The step of the following steps are included:
According toBaseband signal in each group baseband signal group is carried out in quick Fu respectively
Leaf transformation；
In formula, R (i) indicates discrete spectrum sequence, NfftIndicate preset Fast Fourier Transform (FFT) points, r (n) indicates base
The time domain sequences of baseband signal in band signal group, i indicate that Fast Fourier Transform (FFT) point, T indicate the symbol of raw baseband signal
Period.
In the present embodiment, since the symbol numbers of the baseband signal in each group baseband signal group are in preset quick Fu
Leaf transformation points, therefore, can easily be calculated discrete spectrum sequence according to above-mentioned Fast Fourier Transform (FFT) formula.
The step of the disposal of gentle filter is carried out respectively to each group discrete spectrum sequence in one of the embodiments, include with
Lower step:
According toThe disposal of gentle filter is carried out respectively to each group discrete spectrum sequence；
In formula, R ' (k) indicates the first signal spectrum sequence, and W indicates the length of smothing filtering, and R (i) indicates discrete spectrum sequence
Column, i indicate Fast Fourier Transform (FFT) point.
In the present embodiment, spectrum sequence can be made to become more fully apparent using the disposal of gentle filter smooth, by using
Smoothing processing can improve the spectrogram of signal well in low signal-to-noise ratio.
Illustrate the effect of the disposal of gentle filter with specific example below, it is assumed that signal is QPSK (Quadrature
Phase Shift Keyin, abbreviation QPSK, quadrature phase shift keying) signal, setting signal-to-noise ratio is -6dB, obtained original signal
Frequency spectrum and smooth filtered signal spectrum difference are as shown in Figures 2 and 3, and Cong Tuzhong is it is apparent that after smothing filtering
Signal spectrum is high-visible, and the frequency spectrum of original signal is then submerged in and is difficult to recognize in noise.
The step of data investigation processing is carried out to the first signal spectrum sequence of preset group number in one of the embodiments,
The following steps are included:
According toData investigation processing is carried out to the first signal spectrum sequence of preset group number；
In formula, Rm(k) indicate that second signal spectrum sequence, L indicate preset group number, Rj' (k) expression the first signal of jth group frequency
Spectral sequence.
In the present embodiment, although doing the smooth journey that the disposal of gentle filter can be obviously improved signal spectrum to signal is received
Degree, but since under low signal-to-noise ratio, the fluctuation of noise amplitude is larger, thus does frequency deviation using one group of first signal spectrum sequence
Estimation often has very big bounce, and multiple groups the first signal spectrum sequence is carried out data investigation processing, so can reduce noise
The fluctuation of amplitude effectively improves the stability and accuracy of offset estimation.L represent preset group number be it is adjustable, pass through
The precision of offset estimation can be improved by adjusting L, and the first signal spectrum sequence of preset group number is in each group the first signal spectrum sequence
In randomly select.
It obtains stablizing clearly second signal spectrum sequence R in one of the embodiments,m(k) after, second signal is obtained
Maximum amplitude point in spectrum sequence, i.e. target point, the spectrum position of the target point are kmax, spectral magnitude Rm(kmax),
In,It can be with fast search to target point according to formula.
The step of determining the free transmission range of second signal spectrum sequence according to target point in one of the embodiments, include
Following steps:
According toDetermine the free transmission range of second signal spectrum sequence；
In formula, kmaxIndicate the spectrum position of target point, Rm(kmax) indicate target point spectral magnitude, k1And k2Indicate logical
The spectrum position of two endpoints with range, k1≤k’≤k2, k ' indicate free transmission range in each point spectrum position, Rm(k1) and Rm
(k2) indicate free transmission range two endpoints spectral magnitude, Rm(k ') indicates the spectral magnitude of each point in free transmission range.
It in the present embodiment, is that free transmission range is determined according to above-mentioned formula, in frequency spectrum, the unit of spectrum amplitude is
DB, free transmission range are generally the spectral range between peak power and half peak power, be converted into spectral magnitude be exactly with most
Amplitude differs within 3dB, therefore, two endpoints of free transmission range can be determined according to above-mentioned formula, so that it is determined that passband model
It encloses.
In one of the embodiments, obtain free transmission range in amplitude central point the step of the following steps are included:
According toThe spectrum position for obtaining the amplitude central point in free transmission range, in formula,Indicate width
It is worth the spectrum position of central point, k ' indicates the spectrum position of each point in free transmission range, Rm(k ') indicates each in free transmission range
The spectral magnitude of point.
In the present embodiment, after determining free transmission range, according to the spectrum position and spectral magnitude of each point in free transmission range
It can determine the position of amplitude central point, the amplitude central point determining according to formula can reflect the property of spectral passband.
It is obtained in one of the embodiments, according to amplitude central point, Fast Fourier Transform (FFT) points and symbol period former
The step of estimated value of the carrier frequency of primordium band signal the following steps are included:
According toThe estimated value for obtaining the carrier frequency of raw baseband signal, in formula,Indicate original base band
The estimated value of the carrier frequency of signal,Indicate that the spectrum position of amplitude central point, T indicate the symbol week of raw baseband signal
Phase, NfftIndicate preset Fast Fourier Transform (FFT) points.
In the present embodiment, the estimated value that the carrier frequency of raw baseband signal can be obtained according to formula, due to quick
The symbol period of Fourier transformation points and raw baseband signal does not have deviation generally, therefore the estimated value of carrier frequency
Precision is related with the spectrum position of amplitude central point, that is, the position precision of amplitude central point is related；By smothing filtering and
Data investigation makes frequency spectrum more stable and accurate, the position precision height of obtained amplitude central point, and the position of amplitude central point
The precision that precision just determines the estimated value of carrier frequency is set, thus the precision of carrier frequency is also high.
In one of the embodiments, according to the estimated value of the carrier frequency of raw baseband signal and raw baseband signal
The true value of carrier frequency obtain the step of Doppler shift estimated value the following steps are included:
According toDoppler shift estimated value is obtained, in formula,Indicate Doppler shift estimated value,It indicates
The estimated value of the carrier frequency of raw baseband signal, fcIndicate the true value of the carrier frequency of raw baseband signal.
In the present embodiment, Doppler shift estimated value be exactly the carrier frequency of raw baseband signal estimated value with it is original
Difference between the true value of the carrier frequency of baseband signal, in the estimated value and original of the carrier frequency for obtaining raw baseband signal
After the true value of the carrier frequency of primordium band signal, the two, which is subtracted each other, can quickly obtain Doppler shift estimated value.
Digital communication system channel is additive white Gaussian noise channel in one of the embodiments, in baseband signal group
Baseband signal time domain sequences expression formula are as follows:
In formula, r (n) indicates the time domain sequences of the baseband signal in baseband signal group, aiIndicate the base in baseband signal group
Band signal mapping point, A indicate the amplitude of the baseband signal in baseband signal group, and N indicates the baseband signal in baseband signal group
Symbol numbers, T indicate the symbol period of raw baseband signal, NsIndicate he number, TbIndicate that the width of symbol, g indicate pulse
Shaping function, pulse-shaping function duration length is Tb, fcIndicate the true value of the carrier frequency of raw baseband signal,
feIndicate the true value of the Doppler shift of raw baseband signal, θcIndicate the carrier wave initial phase of raw baseband signal, θeIt indicates
The carrier phase deviation of raw baseband signal, w (n) indicate additive white Gaussian noise signal.
In the present embodiment, the f in the expression formula of the time domain sequences of the baseband signal in baseband signal groupeIndicate true
Frequency departure, θeThe carrier phase deviation for indicating baseband signal, from expression formula as can be seen that w (n) is additive white Gaussian noise letter
Number, spectrum curve is the straight line of a steady state value, and carrier frequency item has had more frequency departure fe, it is embodied on discrete spectrum figure just
The f that has been frequency spectrum overall offsete, utilize this information, it is only necessary to which the overall frequency shift amount for finding out receipt signal frequency spectrum is assured that
The carrier deviation f of sending and receiving ende, here it is the basic principles of Doppler shift of the present invention estimation.
Doppler frequency offset estimation method of the invention can be applied to the Doppler of low character rate system under low signal-to-noise ratio
Offset estimation uses multiple groups number wherein using smothing filtering that the signal spectrum under low signal-to-noise ratio is made to emerge out in noise
According to stacking method make frequency spectrum more stable with it is accurate, the frequency deviation of system is then gone out by steady and audible spectrum estimation.Due to
The process employs spectral smoothing filtering and multi-group data superposition processing, allow this method under very low signal-to-noise ratio still
It works normally, thus there is no concern that the threshold effect of snr of received signal.Since this method is carried out to signal carrier frequency spectrum
Estimation, it is unrelated with signal modulation pattern and system symbol rate, thus the frequency deviation estimating method by signal Modulation Types and is not
The limitation of system character rate.In addition, the computation complexity of this method is moderate, thus this method can be widely used in Practical Project
In.
According to above-mentioned Doppler frequency offset estimation method, the present invention also provides a kind of Doppler shift estimating systems, below
The embodiment of Doppler shift estimating system of the invention is described in detail.
It is shown in Figure 4, it is the structural schematic diagram of Doppler shift estimating system in one embodiment of the invention.The implementation
Doppler shift estimating system in example includes with lower unit:
Grouped element 210, for obtaining the raw baseband signal in digital communication system channel, according to preset quick Fu
In leaf transformation points raw baseband signal is grouped, obtain each baseband signal group, wherein the base band of every group of baseband signal group
The symbol numbers of signal are preset Fast Fourier Transform (FFT) points；
Spectrum processing unit 220, for carrying out fast Fourier change respectively to the baseband signal in each group baseband signal group
It changes, obtains the corresponding each group discrete spectrum sequence of each group baseband signal group；
The disposal of gentle filter unit 230 obtains each for carrying out the disposal of gentle filter respectively to each group discrete spectrum sequence
Corresponding the first signal spectrum of each group sequence of group discrete spectrum sequence；
Superposition processing unit 240, for choosing the first signal frequency of preset group number in each group the first signal spectrum sequence
Spectral sequence carries out data investigation processing to the first signal spectrum sequence of preset group number, obtains second signal spectrum sequence；
Passband processing unit 250, for obtaining the target point of amplitude maximum in second signal spectrum sequence, according to target point
It determines the free transmission range of second signal spectrum sequence, and obtains the amplitude central point in free transmission range；
First estimation unit 260, for obtaining the symbol period of raw baseband signal, according to amplitude central point, preset
Fast Fourier Transform (FFT) points and symbol period obtain the estimated value of the carrier frequency of raw baseband signal；
Second estimation unit 270, the true value of the carrier frequency for obtaining raw baseband signal, believes according to original base band
Number carrier frequency estimated value and raw baseband signal carrier frequency true value obtain Doppler shift estimated value.
220 basis of spectrum processing unit in one of the embodiments,To each group base band
Baseband signal in signal group carries out Fast Fourier Transform (FFT) respectively；
In formula, R (i) indicates discrete spectrum sequence, NfftIndicate preset Fast Fourier Transform (FFT) points, r (n) indicates base
The time domain sequences of baseband signal in band signal group, i indicate that Fast Fourier Transform (FFT) point, T indicate the symbol of raw baseband signal
Period.
230 basis of the disposal of gentle filter unit in one of the embodiments,To each group from
Scattered spectrum sequence carries out the disposal of gentle filter respectively；
In formula, R ' (k) indicates the first signal spectrum sequence, and W indicates the length of smothing filtering, and R (i) indicates discrete spectrum sequence
Column, i indicate Fast Fourier Transform (FFT) point.
240 basis of superposition processing unit in one of the embodiments,To the of preset group number
One signal spectrum sequence carries out data investigation processing；
In formula, Rm(k) indicate that second signal spectrum sequence, L indicate preset group number, Rj' (k) expression the first signal of jth group frequency
Spectral sequence.
250 basis of passband processing unit in one of the embodiments,
Determine the free transmission range of second signal spectrum sequence；
In formula, kmaxIndicate the spectrum position of target point, Rm(kmax) indicate target point spectral magnitude, k1And k2Indicate logical
The spectrum position of two endpoints with range, k1≤k’≤k2, k ' indicate free transmission range in each point spectrum position, Rm(k1) and Rm
(k2) indicate free transmission range two endpoints spectral magnitude, Rm(k ') indicates the spectral magnitude of each point in free transmission range.
250 basis of passband processing unit in one of the embodiments,It obtains in free transmission range
The spectrum position of amplitude central point, in formula,Indicate that the spectrum position of amplitude central point, k ' indicate each point in free transmission range
Spectrum position, Rm(k ') indicates the spectral magnitude of each point in free transmission range.
First estimation unit, 260 basis in one of the embodiments,Obtain the carrier wave of raw baseband signal
The estimated value of frequency, in formula,Indicate the estimated value of the carrier frequency of raw baseband signal,Indicate the frequency spectrum of amplitude central point
Position, T indicate the symbol period of raw baseband signal, NfftIndicate preset Fast Fourier Transform (FFT) points.
Second estimation unit, 270 basis in one of the embodiments,Doppler shift estimated value is obtained,
In formula,Indicate Doppler shift estimated value,Indicate the estimated value of the carrier frequency of raw baseband signal, fcIndicate original
The true value of the carrier frequency of baseband signal.
Doppler shift estimating system of the invention and Doppler frequency offset estimation method of the invention correspond, above-mentioned
The technical characteristic and its advantages that the embodiment of Doppler frequency offset estimation method illustrates are suitable for Doppler shift estimation system
In the embodiment of system.
Each technical characteristic of embodiment described above can be combined arbitrarily, for simplicity of description, not to above-mentioned reality
It applies all possible combination of each technical characteristic in example to be all described, as long as however, the combination of these technical characteristics is not deposited
In contradiction, all should be considered as described in this specification.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
It cannot therefore be construed as limiting the scope of the patent.It should be pointed out that coming for those of ordinary skill in the art
It says, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to protection of the invention
Range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
Claims (10)
1. a kind of Doppler frequency offset estimation method, which comprises the following steps:
The raw baseband signal in digital communication system channel is obtained, is counted according to preset Fast Fourier Transform (FFT) to the original
Primordium band signal is grouped, and obtains each baseband signal group, wherein the symbol numbers of the baseband signal of every group of baseband signal group are
The preset Fast Fourier Transform (FFT) points；
Fast Fourier Transform (FFT) is carried out to the baseband signal in each group baseband signal group respectively, obtains each group base band letter
Number corresponding each group discrete spectrum sequence of group；
The disposal of gentle filter is carried out to each group discrete spectrum sequence respectively, it is corresponding to obtain each group discrete spectrum sequence
Each group the first signal spectrum sequence；
The first signal spectrum sequence that preset group number is chosen in the first signal spectrum of each group sequence, to the preset group number
The first signal spectrum sequence carry out data investigation processing, obtain second signal spectrum sequence；
The target point for obtaining amplitude maximum in the second signal spectrum sequence determines the second signal according to the target point
The free transmission range of spectrum sequence, and obtain the amplitude central point in the free transmission range；
The symbol period for obtaining the raw baseband signal becomes according to the amplitude central point, the preset fast Fourier
Change the estimated value that points and the symbol period obtain the carrier frequency of the raw baseband signal；
The true value for obtaining the carrier frequency of the raw baseband signal, according to estimating for the carrier frequency of the raw baseband signal
The true value of the carrier frequency of evaluation and the raw baseband signal obtains Doppler shift estimated value；
The step of free transmission range that the second signal spectrum sequence is determined according to the target point the following steps are included:
According toDetermine the free transmission range of the second signal spectrum sequence；
In formula, kmaxIndicate the spectrum position of the target point, Rm(kmax) indicate spectral magnitude, the k of the target point1And k2Table
Show the spectrum position of two endpoints of the free transmission range, k1≤k′≤k2, k ' indicates each point frequency spectrum position in the free transmission range
It sets, Rm(k1) and Rm(k2) indicate the free transmission range two endpoints spectral magnitude, Rm(k ') is indicated in the free transmission range
Each point spectral magnitude.
2. Doppler frequency offset estimation method according to claim 1, which is characterized in that described to each group baseband signal
The step of baseband signal in group carries out Fast Fourier Transform (FFT) respectively the following steps are included:
According toBaseband signal in each group baseband signal group is carried out in quick Fu respectively
Leaf transformation；
In formula, R (i) indicates the discrete spectrum sequence, NfftIndicate the preset Fast Fourier Transform (FFT) points, r (n) table
Show the time domain sequences of the baseband signal in the baseband signal group, i indicates that Fast Fourier Transform (FFT) point, T indicate the original base
The symbol period of band signal.
3. Doppler frequency offset estimation method according to claim 1, which is characterized in that described to each group discrete spectrum
Sequence carry out the step of the disposal of gentle filter respectively the following steps are included:
According toThe disposal of gentle filter is carried out respectively to each group discrete spectrum sequence；
In formula, R ' (k) indicates the first signal spectrum sequence, and W indicates the length of smothing filtering, and R (i) indicates the discrete frequency
Spectral sequence, i indicate Fast Fourier Transform (FFT) point.
4. Doppler frequency offset estimation method according to claim 1, which is characterized in that described to the of the preset group number
One signal spectrum sequence carry out data investigation processing the step of the following steps are included:
According toData investigation processing is carried out to the first signal spectrum sequence of the preset group number；
In formula, Rm(k) indicate that the second signal spectrum sequence, L indicate the preset group number, Rj' (k) expression letter of jth group first
Number spectrum sequence.
5. Doppler frequency offset estimation method according to claim 1, which is characterized in that described to obtain in the free transmission range
Amplitude central point the step of the following steps are included:
According toObtain the spectrum position of the amplitude central point in the free transmission range, in formula,Indicate institute
The spectrum position of amplitude central point is stated, k ' indicates the spectrum position of each point in the free transmission range, Rm(k ') indicates described logical
Spectral magnitude with each point in range.
6. Doppler frequency offset estimation method according to claim 1, which is characterized in that described according to the amplitude center
Point, Fast Fourier Transform (FFT) points and the symbol period obtain the estimated value of the carrier frequency of the raw baseband signal
The step of the following steps are included:
According toObtain the estimated value of the carrier frequency of the raw baseband signal, in formula,Indicate described original
The estimated value of the carrier frequency of baseband signal,Indicate that the spectrum position of the amplitude central point, T indicate the original base band letter
Number symbol period, NfftIndicate the preset Fast Fourier Transform (FFT) points.
7. Doppler frequency offset estimation method according to claim 1, which is characterized in that described to be believed according to the original base band
Number carrier frequency estimated value and the raw baseband signal carrier frequency true value obtain Doppler shift estimated value
The step of the following steps are included:
According toObtain the Doppler shift estimated value, in formula,Indicate the Doppler shift estimated value,
Indicate the estimated value of the carrier frequency of the raw baseband signal, fcIndicate the true of the carrier frequency of the raw baseband signal
Value.
8. Doppler frequency offset estimation method as claimed in any of claims 1 to 7, which is characterized in that the number
Communication system channel is additive white Gaussian noise channel, the expression formula of the time domain sequences of the baseband signal in baseband signal group are as follows:
In formula, r (n) indicates the time domain sequences of the baseband signal in baseband signal group, aiIndicate the baseband signal in baseband signal group
Mapping point, A indicate the amplitude of the baseband signal in baseband signal group, and N indicates the symbol of the baseband signal in baseband signal group
Number, T indicate the symbol period of raw baseband signal, NsIndicate he number, TbIndicate that the width of symbol, g indicate pulse-shaping letter
Number, pulse-shaping function duration length is Tb, fcIndicate the true value of the carrier frequency of raw baseband signal, feIt indicates
The true value of the Doppler shift of raw baseband signal, θcIndicate the carrier wave initial phase of raw baseband signal, θeIndicate original base
The carrier phase deviation of band signal, w (n) indicate additive white Gaussian noise signal.
9. a kind of Doppler shift estimating system, which is characterized in that including with lower unit:
Grouped element becomes for obtaining the raw baseband signal in digital communication system channel according to preset fast Fourier
It changes points to be grouped the raw baseband signal, obtains each baseband signal group, wherein the base band letter of every group of baseband signal group
Number symbol numbers be the preset Fast Fourier Transform (FFT) points；
Spectrum processing unit, for carrying out Fast Fourier Transform (FFT) respectively to the baseband signal in each group baseband signal group,
Obtain the corresponding each group discrete spectrum sequence of each group baseband signal group；
The disposal of gentle filter unit, for carrying out the disposal of gentle filter respectively to each group discrete spectrum sequence, described in acquisition
Corresponding the first signal spectrum of each group sequence of each group discrete spectrum sequence；
Superposition processing unit, for choosing the first signal spectrum sequence of preset group number in the first signal spectrum of each group sequence
Column carry out data investigation processing to the first signal spectrum sequence of the preset group number, obtain second signal spectrum sequence；
Passband processing unit, for obtaining the target point of amplitude maximum in the second signal spectrum sequence, according to the target
Point determines the free transmission range of the second signal spectrum sequence, and obtains the amplitude central point in the free transmission range；
First estimation unit, for obtaining the symbol period of the raw baseband signal, according to the amplitude central point, described pre-
If Fast Fourier Transform (FFT) points and the symbol period obtain the raw baseband signal carrier frequency estimated value；
Second estimation unit, the true value of the carrier frequency for obtaining the raw baseband signal, according to the original base band
The true value of the carrier frequency of the estimated value of the carrier frequency of signal and the raw baseband signal obtains Doppler shift estimation
Value；
The passband processing unit according toDetermine second signal spectrum sequence
Free transmission range；
In formula, kmaxIndicate the spectrum position of target point, Rm(kmax) indicate target point spectral magnitude, k1And k2Indicate passband model
The spectrum position of two endpoints enclosed, k1≤k’≤k2, k ' indicate free transmission range in each point spectrum position, Rm(k1) and Rm(k2)
Indicate the spectral magnitude of two endpoints of free transmission range, Rm(k ') indicates the spectral magnitude of each point in free transmission range.
10. Doppler shift estimating system according to claim 9, which is characterized in that the spectrum processing unit according toFast Fourier Transform (FFT) is carried out respectively to the baseband signal in each group baseband signal group；
In formula, R (i) indicates discrete spectrum sequence, NfftIndicate preset Fast Fourier Transform (FFT) points, r (n) indicates base band letter
The time domain sequences of baseband signal in number group, i indicate that Fast Fourier Transform (FFT) point, T indicate the symbol period of raw baseband signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610602159.XA CN106230762B (en) | 2016-07-26 | 2016-07-26 | Doppler frequency offset estimation method and system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610602159.XA CN106230762B (en) | 2016-07-26 | 2016-07-26 | Doppler frequency offset estimation method and system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN106230762A CN106230762A (en) | 2016-12-14 |
| CN106230762B true CN106230762B (en) | 2019-06-18 |
Family
ID=57533200
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201610602159.XA Active CN106230762B (en) | 2016-07-26 | 2016-07-26 | Doppler frequency offset estimation method and system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN106230762B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112217756B (en) * | 2019-07-12 | 2022-03-29 | 华为技术有限公司 | Doppler frequency offset estimation method and communication device |
| CN114422314B (en) * | 2021-12-22 | 2024-05-24 | 江苏科大亨芯半导体技术有限公司 | Multi-carrier frequency discrimination method and system |
| CN114978828B (en) * | 2022-05-07 | 2023-04-28 | 广州海格通信集团股份有限公司 | Frequency offset estimation method and device, electronic equipment and storage medium |
| CN116520262B (en) * | 2023-06-25 | 2023-10-17 | 成都华兴汇明科技有限公司 | Radar interference signal generation method and system based on vector signal source |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1980208A (en) * | 2005-12-02 | 2007-06-13 | 华为技术有限公司 | Carrier-wave frequency deviation estimation method in communication system, apparatus and system therefor |
| CN101667989A (en) * | 2009-09-16 | 2010-03-10 | 中兴通讯股份有限公司 | Signal carrier frequency and phase position estimating method and device |
| CN102006256A (en) * | 2009-09-03 | 2011-04-06 | 卓胜微电子（上海）有限公司 | Estimation method of integral multiple subcarrier frequency offset of robust |
| CN104852875A (en) * | 2015-03-26 | 2015-08-19 | 中国人民解放军理工大学通信工程学院卫星通信军队重点实验室 | Frequency offset estimation method for high-dynamic large-frequency-offset burst signals |
-
2016
- 2016-07-26 CN CN201610602159.XA patent/CN106230762B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1980208A (en) * | 2005-12-02 | 2007-06-13 | 华为技术有限公司 | Carrier-wave frequency deviation estimation method in communication system, apparatus and system therefor |
| CN102006256A (en) * | 2009-09-03 | 2011-04-06 | 卓胜微电子（上海）有限公司 | Estimation method of integral multiple subcarrier frequency offset of robust |
| CN101667989A (en) * | 2009-09-16 | 2010-03-10 | 中兴通讯股份有限公司 | Signal carrier frequency and phase position estimating method and device |
| CN104852875A (en) * | 2015-03-26 | 2015-08-19 | 中国人民解放军理工大学通信工程学院卫星通信军队重点实验室 | Frequency offset estimation method for high-dynamic large-frequency-offset burst signals |
Also Published As
| Publication number | Publication date |
|---|---|
| CN106230762A (en) | 2016-12-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106230762B (en) | Doppler frequency offset estimation method and system | |
| US7860193B2 (en) | Coarse timing estimation system and methodology for wireless symbols | |
| CN101667989B (en) | Signal carrier frequency and phase position estimating method and device | |
| US10944612B2 (en) | System and method for frequency synchronization of Doppler-shifted subcarriers | |
| CN101909024B (en) | Method and device for estimating maximum Doppler frequency offset | |
| CN109600328A (en) | Stablize modulation index calibration and dynamic controls | |
| CN102868659B (en) | Symbol synchronization and Doppler compensation method for mobile orthogonal frequency division multiplexing (OFDM) underwater sound communication signal | |
| CN106059973B (en) | Frequency deviation estimating method and system | |
| CN109067680B (en) | Carrier frequency offset estimation method and device of baseband signal | |
| EP3079264B1 (en) | Spread spectrum signal generating method, generating apparatus, receiving method and receiving apparatus | |
| CN101401380A (en) | Frequency tracking which adapts to timing synchronization | |
| CN103856431B (en) | The lower open-loop carrier synchronized algorithm of MPSK modulation based on fast Fourier transform | |
| CN111935046B (en) | Low-complexity frequency shift keying signal symbol rate estimation method | |
| CN105635002A (en) | Synchronization estimation method and receiving end device | |
| CN101801066B (en) | Method for Implementing Cell Search in Wireless Communication System | |
| US20040151142A1 (en) | Method and device for OFDM carrier frequency synchronization | |
| JP2008211760A (en) | Modulation system estimation apparatus | |
| CN103748846A (en) | Method and module for estimating frequency bias in a digital-telecommunications system | |
| CN102655491B (en) | Frequency shift estimation method and system for coherent demodulation frequency shift keying modulating signals | |
| CN101242390B (en) | Carrier Frequency Offset Estimation Algorithm and Implementation Device Based on Known Sequence Coherent Autocorrelation | |
| CN110430156B (en) | Frame synchronization method and system for burst OFDM data transmission | |
| CN105406921A (en) | MFSK water sound communication method and MFSK water sound communication system | |
| CN109633709B (en) | Practical and efficient frequency offset estimation method in satellite communication system | |
| CN108270707B (en) | Signal synchronization method and device | |
| CN106302286A (en) | A kind of signal to noise ratio blind estimating method of ofdm system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |